NOTATION IS KEY

Plasticity is one of the best tricks that our brain possesses; the ability to reorganize pathways and synapses in response to envoirmental pressures and biological needs. In short: it helps us learn. This ability lasts throughout your entire life. That means that we are never too old to learn and for the brain to change- and learning to play an instrument or sing is a powerful way to stimulate the mind.
How much can music change the way that your brain looks and works? There is little evidence so far that just listening to lots of music causes any significant changes to the brain structure or function. By contrast, there is a long history of exploring the changes that may occur as a result of musical training.In the early 20th century a German surgeon names Sigmund Auerbach conducted a series of post-mortem brain dissections on five famous musicians of that time. Dr. Auerbach wanted to see where and how their brains were different to the average one that he saw every day on his operating table. Auerbach concluded that all five individuals had enlargements in the middle and back areas of the superior temporal gyrus (the areas in the brain that processes sounds). All in all, the brain differences he saw were not extensive, but remember we are talking about things that could be seen with the human eye and a magnifying glass.
Fortunately, the development of brain imaging techniques such as magnetic resonance imaging (MRI) in the 20th century made it possible to obtain thee dimensional, high resolution images of the living brain instead of having to wait around for famous musicians to pass away.

One of the earliest (1995) brain imaging studies conducted by Gottfried Schlaug and colleagues reported that the corpus calossum (a series of neutral fibre connections that holds the two hemispheres of your brain together) was significantly larger in 30 professional right handed keyboard and string musicians compared to 30 non-musically trained individuals. Moreover, the difference was driven mostly by people who started their musical training before the age of seven. The conclusion ws that the need for complex bimanual coordination when playing keyboard or string instruments necessitates growth in the brain area that facilitated communication between the hands.
Not only is the corpus callosum bigger in some professional musicians, it also has a different way of working. You get faster transfer of all kinds of information (including visual) between the hemispheres in musicians compared to non-musicians.

The corpus callosum is not the only point of connectivity in the brain. The whole structure is covered in white matter pathways whose job it is to transfer signals between different parts of the brain.
A large study of professional pianists carried out at University College of London found several areas of the brain where white matter fibres were denser, better aligned and with a more effective protective layer that counts the outside of the neurons. This finding was associated with practice; the more someone practiced, the denser the white matter. This finding hints at improvement connectivity in a number of important brain regions outside the corpus callossum in musicians.

The enhanced connectivity effect is not limited to instrumental learning either. A study conducted by Gus Halwani and colleagues tested the integrity of a particular large white matter pathway (or ‘tract’) known as the arcuate fascisculus (AF). The AF connects the temporal and frontal lobes and is a very important pathway for carrying information about sound. We have two AF tracts, one in the right hemisphere and one in the left. Hallway and his team measured the volume and the density of the fibres in the AF tracts in both hemispheres in non-musicians, instrumental musicians and vocal musicians. The AF tract was larger end denser in musicians compared to non-musicians. Interestingly, in the left hemisphere, parts of the AF were bigger in singers compared to instrumentalists but were also less dense, meaning the fibres in the AF at these point were to be more criss-crossed or branching.
Why the difference in the left and right AF in the singers? The theory is that the left side of the brain may be more focussed on the demands of producing speech while the right side is more interested in all types of sound more generally.

The great point about this study is that it hints that you may get a boost effect in brain connectivity from singing, which is something that we can all attempt in our everyday lives without the need for an instrument.